Charging Batteries

[josephL]

I suspect my problem has been well documented so please bear with me. I currently have a 2.4 kw off grid system with all Outback equipment. My battery bank is twelve lead acid batteries wired in series 70 pound each. I use propane for domestic hot water, cooking and keep the house (which I don’t live in) heated to 50 degrees through the winter. I worked with my solar installer on the entire system which has functioned perfectly for the past 5 years. on three occasions over those years I have hooked up a small Honda Generator to charge the batteries. This has created some stressful times trying to guess where the battery levels might be what the coming weather is, has the snow melted off and so on. on top of that I have a 3/4 mile trail for a driveway, access can be very difficult in the winter.

Determined to find a solution I recently settled on purchasing a Kohler 14kw RCA and use a Magnum Energy AGS auto start to bypass the inverter for starting the generator remotely when the voltage drops to a specified level. My current inverter has only one dc remote Connection which is dedicated to the battery box vent fan. That was where I was at until I ran into this forum which got me wondering if there was a less expensive solution that would function with the Magnum AGS. Ideally this setup would allow me to use portable propane among other less costly solutions. (Kohler generator is 5.5K with tax) Any thoughts or suggestions would be greatly appreciated. Thanks
Joe

 

[MisterSandals]

My battery bank is twelve lead acid batteries wired in series 70 pound each.

Do you have a better description of your battery bank than its weight? Any pics or diagrams? 12 batteries can be wired quite a few ways. Many bad ways to wire it and very few good ways too.

12 x 12V batteries in series is 144V which is mighty unusual.

 

[pollenface]

My current inverter has only one dc remote Connection which is dedicated to the battery box vent fan. That was where I was at until I ran into this forum which got me wondering if there was a less expensive solution that would function with the Magnum AGS.

Use a different means to power the "battery box vent fan" and use the remote connection as required.

Furthermore, does your battery box really need a fan?

Do you have a better description of your battery bank than its weight?

120ah AGMs are roughly 70lbs if that's anything to go by

 

[josephL]

Here is a picture of the batteries 12 X 2 volt wired in series. Pretty sure it’s setup just fine. Not sure how I would set the battery fan up differently unless it was set to run continuousl, I suppose that might be possible?

 

[pollenface]

Why do you need a battery fan? Sounds strange.

A ventilated space without a fan is usually fine.

In the past I have used a small 10w solar panel connected directly to a couple of computer fans to cool my MPPTs

 

[josephL]

If I remove the lid to the battery box you smell the off gassing immediately, the mechanical room is off in a corner, not very well ventilated. Pretty sure the vent is a good idea.

 

[Supervstech]

If I remove the lid to the battery box you smell the off gassing immediately, the mechanical room is off in a corner, not very well ventilated. Pretty sure the vent is a good idea.

Nobody said ya don't need a vent, they said a fan isn't needed.
A low and a high opening is wise.

 

[josephL]

I already have a high low vent with the high side tied into the vent but I’m disinclined to disconnect the fan?‍.
here is another question; the few times I‘ve used my little Honda inverter to charge the batteries I would get 3 percent increase in the batteries per hour. I’m wondering if that will improve with a bigger generator. Any thoughts? Thank You

 

[MisterSandals]

inverter to charge the batteries I would get 3 percent increase in the batteries per hour.

What is the size of your battery? What is the output of your Honda inverter generator?

I’m wondering if that will improve with a bigger generator

What is the manufacturer recommended max charging rate?

 

[josephL]

Thanks, sorry I’m such a Luddite. 12 2 volt batteries 70lbs each don’t know how many amp hours they have but they do a good job of running a small house. Generator is the smallest Honda 2200 watt. Inverter is Outback GVFX3524.
don’t know if that provides you with any good info or not.

 

[MisterSandals]

Ok, thats a very big battery.
2200W / 28V charging = 78A max from that generator.

Have you done regular maintenance on the batteries? this would involve checking the specific gravity and making sure the water levels are correct. Keeping a log on each of your (labeled!) cells with this info as well as the corresponding at rest voltages will go a long way in your maintenance.

 

[josephL]

I’ve done a marginal job of battery maintenance. Checked the specific gravity about 1-1/2 years ago, all the cells except one were good. I have completely failed at Equalization, started the process once and the batteries boiled over, it did complete the cycle, I think. I have religiously kept them topped off with distilled water. I can tell they have lost some of their vitality by how much they discharge over night, and yet they are still fairly robust after five years. I will most likely proceed with the Magnum AGS with a bigger generator and portable propane.